1. Field of the Invention
This present invention is related to threshold level setting circuits and more particularly to a circuit for use in combination with an interface system to make such system compatible with both T.sup.2 L and CMOS logic.
2. Description of the Prior Art
Nearly all interface systems require a threshold setting function in order that they be compatible with several different logic signal drive. For example, digital to analog converters (DACs) are a type of interface circuit which in most cases should be capable of accommodating T.sup.2 L or CMOS logic input signals. In addition to interfacing easily with T.sup.2 L or CMOS logic, DACs as aforementioned should also be able to operate with either logic using either +5 volt or .+-.15 volt supplies.
Hence, there is a need for a simple logic select circuit suitable to be manufactured on "chip" with an integrated interface system to provide multiple threshold level for the system without requiring external circuitry in order to make the interface system compatible with several different logic input signals that may be supplied thereto and which can operate from either a 5 volt or 15 volt power supply.